As a rolling bearing on which a wheel of a vehicle such as a motor vehicle is mounted, there is, for example, a rolling bearing which includes an outer ring and an inner ring which is provided on the outer ring via rolling elements. In addition, a sensor device for detecting a rotating speed of a wheel is used to control an anti-lock braking system (ABS) of a motor vehicle, and there is known a configuration in which the sensor device is mounted on a sealing device for sealing an annular space between the outer ring and the inner ring so as to be integrated into the sealing device to thereby realize miniaturization of the sensor device.
As a sensor device provided on the sealing device, there is a sensor device as is shown in FIG. 5, for example, which includes a metal core 103 which is fixed to an inner circumference of an outer ring 107, which is a fixed ring, a sealing main body 106 which is attached to an inner circumferential side of the metal core 103, a magnetic encoder 101 made up of a metallic slinger 102 which is fixed to an outer circumference of an inner ring 108, which is a rotating ring, and an annular magnetized member 104 which is bonded to an outer (a right-hand side in FIG. 5) and on which N poles and S poles are magnetized alternately in a circumferential direction, and a sensor 105 which is disposed to face the magnetic encoder 101. In this sensor device, a rotating speed of a wheel is detected by the sensor 105 a change in magnetic flux generated by rotation of the magnetic encoder 101 together with the inner ring 108 (for example, refer to Patent Documents 1, 2).    Patent Document 1: JP-A-2006-90956    Patent Document 2: JP-A-2006-90995